Many cancers arise from differentiated tissues that are slowly dividing. The initial malignant population may have developed from a small, rapidly proliferating population of residual tissue stem cells or cells with a less differentiated subcellular profile. A strategy for targeting tumor cells that are antigenically distinct from mature differentiated cells could be useful in the treatment of cancer, particularly for controlling microscopic spread of disease. Malignant cells may express receptors used in embryonic patterning, which may serve as immunologic targets distinct from mature differentiated tissue.
In embryogenesis body patterning is related to the axial expression of different proteins. The proximal-distal axis is controlled by fibroblast growth factor (Vogel, A. et al., “Involvement of FGF-8 in initiation, outgrowth and patterning of the vertebrate limb,” Development, 122:1737-1750 (1996); Vogel, A. and Tickle, C., “FGF-4 maintains polarizing activity of posterior limb bud cells in vivo and in vitro,” Development 119:199-206 (1993); Niswander, L. et al., “FGF-4 replaces the apical ectodermal ridge and directs outgrowth and patterning of the limb,” Cell 75:579-587 (1993)), anterior-posterior axis by Sonic hedgehog (Riddle, R. D. et al, “Sonic hedgehog mediates the polarizing activity of the ZPA,” Cell 75:1401-1416 (1993)), and the dorsal ventral axis by wingless (Parr, B. A. et al., “Mouse Wnt genes exhibit discrete domains of expression in the early embryonic CNS and limb buds,” Development 119:247-261 (1993); Riddle, R. D. et al., “Induction of the LIM homeobox gene Lmx1 by Wnt7a establishes dorsoventral pattern in the vertebrate limb,” Cell 83:631-640 (1995); Vogel, A. et al., “Dorsal cell fate specified by chick Lmx1 during vertebrate limb development,” Nature 378:716-720 (1995)). These factors are closely cross-regulated in development. The secretion of Wnt (wingless) is stimulated by Sonic hedgehog (SHH) signaling and conversely the expression of SHH is supported by the continued presence of wingless. SHH in turn influences fibroblast growth factor (FGF) expression (Niswander, L. et al., “A positive feedback loop coordinates growth and patterning in the vertebrate limb,” Nature 371:609-612 (1994); Niswander, L., et al., “Function of FGF-4 in limb development,” Mol Reprod Dev 39:83-88; discussion 88-89 (1994); Laufer, E. et al., “Sonic hedgehog and Fgf-4 act through a signaling cascade and feedback loop to integrate growth and patterning of the developing limb bud,” Cell 79:993-1003 (1994)). Wingless is a ligand for a G-coupled protein receptor named frizzled, which mediates a complex signaling cascade (Vinson, C. R. and Adler, P. N., “Directional non-cell autonomy and the transmission of polarity information by the frizzled gene of Drosophila,” Nature 329:549-551 (1987)). Transcriptional regulation is also mediated by SHH cell surface interaction with its ligand, Patched. Patched tonically inhibits signaling through Smoothened until it binds to SHH. These pathways are illustrated in FIG. 1, which has been adapted from reviews by others (Hunter, T., “Oncoprotein networks,” Cell 88:333-346 (1997); Ng, J. K. et al., “Molecular and cellular basis of pattern formation during vertebrate limb development,” Curr Top Dev Biol 41:37-66 (1999); Ramsdell, A. F. and Yost, H. J., “Molecular mechanisms of vertebrate left-right development,” Trends Genet 14:459-465 (1998)).
Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer in developed countries, and of the 44,000 annual cases reported in the United States approximately 11,000 will result in an unfavorable outcome (Landis, S. H. et al., “Cancer statistics,” CA Cancer J Clin. 49, 8-31 (1999); Parkin, D. M. et al., “Global cancer statistics,” CA Cancer J Clin. 49, 33-64 (1999)). Although metastatic HNSCC can respond to chemotherapy and radiotherapy, it is seldom adequately controlled. Therefore, it is important to identify new molecular determinants on HNSCC that may be potential targets for chemotherapy or immunotherapy.
In APC-deficient colon carcinoma, beta-catenin accumulates and is constitutively complexed with nuclear Tcf-4 (Sparks, A. B. et al., “Mutational analysis of the APC/beta-catenin/Tcf pathway in colorectal cancer,” Cancer Res 58:1130-1134 (1998)). Other colon carcinomas and melanomas also contain constitutive nuclear Tcf-4/beta-catenin complexes as a result of mutations in the N terminus of beta-catenin that render it insensitive to downregulation by APC, and GSK3 beta (Morin, P. J. et al., “Activation of beta-catenin-Tcf signaling in colon cancer by mutations in beta-catenin or APC,” Science 275:1787-1790 (1997); Rubinfeld, B. et al. “Stabilization of beta-catenin by genetic defects in melanoma cell lines,” Science 275:1790-1792 (1997)). This results in the unregulated expression of Tcf-4 oncogenic target genes, such as c-myc, cyclin D1, and c-jun (He, T. C. et al., “Identification of C-MYC as a target of the APC pathway,” Science 281:1509-1512 (1998); Shtutman, M. et al., “The cyclin D1 gene is a target of the beta-catenin/LEF-1 pathway,” Proc. Nat'l. Acad Sci. USA 96:5522-5527 (1999); Li, L. et al., “Disheveled proteins lead to two signaling pathways. Regulation of LEF-1 and c-Jun N-terminal kinase in mammalian cells,” J Biol Chem 274:129-134 (1999)). The expression of covalently linked beta-catenin and LEF-1 has been directly demonstrated to result in the oncogenic transformation of chicken fibroblasts (Aoki, M. et al, “Nuclear endpoint of Wnt signaling: neoplastic transformation induced by transactivating lymphoid-enhancing factor 1,” Proc. Nat'l. Acad. Sci. USA 96:139-144 (1999)). Similar mechanisms leading to deregulation of Tcf target gene activity are likely to be involved in melanoma (Rimm, D. L. et al., “Frequent nuclear/cytoplasmic localization of beta-catenin without exon 3 mutations in malignant melanoma,” Am J Pathol 154:325-329 (1999)), breast cancer (Bui, T. D. et al., “A novel human Wnt gene, WNT10B, maps to 12q13 and is expressed in human breast carcinomas,” Oncogene 14:1249-1253 (1997)), heptocellular carcinoma (de La Coste, A. et al., “Somatic mutations of the beta-catenin gene are frequent in mouse and human heptocellular carcinomas,” Proc Nat'l. Acad. Sci. USA 95:8847-8851 (1998)), ovarian cancer (Palacios, J., and Gamallo, C., “Mutations in the beta-catenin gene (CTNNB1) in endometrioid ovarian carcinomas,” Cancer Res 58:1344-1347 (1998)), endometrial cancer (Ikeda, T., “Mutational analysis of the CTNNB1 (beta-catenin) gene in human endometrial cancer: frequent mutations at codon 34 that cause nuclear accumulation,” Oncol Rep 7:323-326 (2000)), medulloblastoma (Hamilton, S. R. et al., “The molecular basis of Turcot's syndrome,” N. Engl J Med 332:839-847 (1995)), pilomatricomas (Chan, E. F. et al. “A common human skin tumour is caused by activating mutations in beta-catenin,” Nat. Genet 21:410-413 (1999)), and prostate cancer (Iozzo, R. V. et al., “Aberrant expression of the growth factor Wnt-5A in human malignancy,” Cancer Res 55:3495-3499 (1995)).
Other growth regulation pathways in tumors have also attracted recent interest. Many epithelial tumors express excess amounts of epidermal growth factor-receptor tyrosine kinases, particularly epidermal growth factor receptor (EGFR, or ErbB-1), and HER2 (ErbB-2) (Coussens, L. et al, “Tyrosine kinase receptor with extensive homology to EGF receptor shares chromosomal location with neu oncogene,” Science 230:1132-1139 (1985); King, C. R. et al., “Amplification of a novel v-erbB-related gene in a human mammary carcinoma,” Science 229:974-976 (1985)). HER2 is transmembrane tyrosine kinase receptor, which dimerizes with another member of the EGFR family to form an active dimeric receptor (Akiyama, T. et al., “The product of the human c-erbB-2 gene: a 185-kilodalton glycoprotein with tyrosine kinase activity,” Science 232:1644-1646 (1986)). The resulting phosphorylation of tyrosine residues initiates complex signaling pathways that ultimately lead to cell division. HER2 is overexpressed in 25 to 30 percent of breast cancers, usually as a result of gene amplification (Slamon, D. J. et al., “Studies of the HER-2/neu proto-oncogene in human breast and ovarian cancer,” Science 244:707-712 (1989)). A high level of this protein is associated with an adverse prognosis (Slamon, D. J. et al., “Human breast cancer: correlation of relapse and survival with amplification of the HER-2/neu oncogene,” Science 235:177-182 (1987); Ravdin, P. M. and Chamness, G. C., “The c-erbB-2 proto-oncogene as a prognostic and predictive marker in breast cancer: a paradigm for the development of other macromolecular markers—a review,” Gene 159:19-27 (1995)).
In the past decade there has been tremendous progress in identifying genetic and molecular changes that occur during the transformation of malignant cells. Many malignant cells have a less differentiated phenotype, and a higher growth fraction than normal in adult tissues. These basic characteristics are similar to immature or embryonic cells. During the development of the embryo, various cell surface receptors and ligands direct tissue pattern formation, and cellular differentiation (Hunter, T., “Oncoprotein networks,” Cell 88, 333-346 (1997); Ng, J. K. et al., “Molecular and cellular basis of pattern formation during vertebrate limb development,” Curr Top Dev Biol. 41, 37-66 (1999); Ramsdell, A. F. and Yost, H. J., “Molecular mechanisms of vertebrate left-right development,” Trends Genet. 14, 459-465 (1998)). The expression of these receptors and ligands is often no longer required in fully matured adult tissues. Because they are expressed on the cell surface, the receptors and ligands important for morphologic patterning and tissue differentiation could be targets for the immunotherapy of tumors that have arisen from residual immature cells, or that have undergone de-differentiation.
Genes of the wingless (Wnt) and frizzled (Fzd) class have an established role in cell morphogenesis and cellular differentiation (Parr, B. A. et al., “Mouse Wnt genes exhibit discrete domains of expression in the early embryonic CNS and limb buds,” Development, 119, 247-261 (1993); Riddle, R. D. et al., “Induction of the LIM homeobox gene Lmx1 by WNT7a establishes dorsoventral pattern in the vertebrate limb,” Cell 83, 631-640 (1995); Vogel, A. et al., (1995) “Dorsal cell fate specified by chick Lmx1 during vertebrate limb development,” Nature 378, 716-720 (1995)). The Wnt proteins are extracellular ligands for the Fzd receptors, which resemble typical G protein coupled receptors (GPCRs). The first member of the 19 known human Wnt genes, Wnt-1, was initially discovered because of its oncogenic properties (Nusse, R. and Varmus, H. E., “Many tumors induced by the mouse mammary tumor virus contain a provirus integrated in the same region of the host genome,” Cell 31, 99-109 (1982)). The Wnt glycoproteins bind to one or more of the 10 known, 7 transmembrane domain G-protein coupled Fzd receptors, to initiate a chain of signaling events that often culminates in the stabilization and nuclear translocation of β-catenin, with resultant heterodimerization with one of the four members of the LEF/TCF family of transcription factors (Cadigan, K. M. and Nusse, R., “Wnt signaling: a common theme in animal development,” Genes Dev., 11, 3286-3305 (1997); Miller, J. R. et al., “Mechanism and function of signal transduction by the Wnt/β-catenin and Wnt/Ca2+ pathways,” Oncogene 18, 7860-7872 (1999)). These transcription factor complexes control the activities of specific Wnt target genes, including developmental regulators and other genes involved in coordinating cell proliferation, cell-cell interactions, and cell-matrix interactions (Vogel, A. and Tickle, C., “FGF-4 maintains polarizing activity of posterior limb bud cells in vivo and in vitro,” Development 119:199-206 (1993)). The overexpression of β-catenin and LEF-1 has been demonstrated to result in the oncogenic transformation of chicken fibroblasts (Aoki, M. et al., “Nuclear endpoint of Wnt signaling: neoplastic transformation induced by transactivating lymphoid-enhancing factor 1,” Proc. Nat'l. Acad. Sci. USA 96, 139-144 (1999)).
A recent survey using microarray techniques showed that most HNSCC overexpress mRNAs of the Wnt family (Leethanakul, C. et al., “Distinct pattern of expression of differentiation and growth-related genes in squamous cell carcinomas of the head and neck revealed by the use of laser capture microdissection and cDNA arrays,” Oncogene 19, 3220-3224 (2000)). However, the various Wnt mRNAs are very homologous, and hybridization in microarrays often cannot distinguish between closely related templates.
A murine monoclonal antibody 4DS binds with high affinity to the extracellular domain of HER2, thereby blocking its function in signal transduction (Hudziak, R. M. et al. “p185HER2 monoclonal antibody has antiproliferative effects in vitro and sensitizes human breast tumor cells to tumor necrosis factor,” Mol Cell Biol 9:1165-1172 (1989); Fendly, B. M. et al. “Characterization of murine monoclonal antibodies reactive to either the human epidermal growth factor receptor or HER2/neu gene product,” Cancer Res 50:1550-1558 (1990); Fendly, B. M. et al. “The extracellular domain of HER2/neu is a potential immunogen for active specific immunotherapy of breast cancer,” J Biol Response Mod 9:449-455 (1990)). In experimental models of breast cancer, it was active in vitro and in vivo, and had greater anti-tumor effects when combined with chemotherapy Hudziak, R. M. et al. “p185HER2 monoclonal antibody has antiproliferative effects in vitro and sensitizes human breast tumor cells to tumor necrosis factor,” Mol Cell Biol 9:1165-1172 (1989); Pietras, R. J. et al., “Antibody to HER-2/neu receptor blocks DNA repair after cisplatin in human breast and ovarian cancer cells,” Oncogene 9:1829-1838 (1994). A recently completed phase 3 randomized clinical trial of a humanized form of 4DS monoclonal antibody, trastuzumab (Herceptin; Genentech, Inc, South San Francisco, Calif.), demonstrated efficacy against some forms of breast tumors overexpressing HER2 (Slamon, D. J. et al., “Use of chemotherapy plus a monoclonal antibody against HER2 for metastatic breast cancer that overexpresses HER2,” N Engl J Med 344:783-792 (2001).